iPhone, Android and the WeChat mini program are supported; you can also just scan the QR code with your phone's browser.
Make sure you are on 4.0 or newer — 4.0 on the desktop uses a new connect ladder (LAN, cloud signalling, QR code, USB) that older app builds cannot answer. Search for design mirror in your app store.

The app makes live preview convenient
You can pinch to zoom your design when need. some useful preview modes are provided.
You can swipe to navigate artboards/documents, or select one by name.
Take a screenshot when you wanna save a design on your mobile phone.
Transfer image from phone to Photoshop/Sketch never so easy.
Artboards previewed are saved in app, you can check it anytime.
Easy share your design with in app share button.
